1. Field of the Invention
The present invention relates to an apparatus for displaying the conditions of the surroundings of a movable body, and more particularly to an apparatus for capturing and displaying an image of a surrounding area which, if an obstacle is present in the surrounding area, displays on the captured image an area in which the obstacle is present.
2. Description of the Related Art
Japanese Patent Application Laid-Open (kokai) Nos. 3-85069, 2-299944, and 2000-184368 disclose conventional apparatuses for displaying surrounding conditions of a vehicle, which is a movable body. The apparatus of Japanese Patent Application Laid-Open No. 3-85069 displays a distance to an obstacle on a screen which displays an image of an area at the back of a vehicle (hereinafter referred to as a “back area image”), in such a manner that the distance is displayed in a bottom region of the screen in the form of a graph. The apparatus of Japanese Patent Application Laid-Open No. 2-299944 extracts a contour of an obstacle from a back area image of a vehicle, estimates a distant to the obstacle from the width of the contour; and colors a displayed image of the obstacle in a color corresponding to the distance to the obstacle. The apparatus of Japanese Patent Application Laid-Open No. 2000-184368 superposes a contour image of an obstacle or a symbol image on a back area image of a vehicle.
However, none of the apparatuses disclosed in the above-described patent publications display, on a back area image, an area in which an obstacle is present, because the apparatuses of Japanese Patent Application Laid-Open Nos. 2-299944 and 2000-184368 display an obstacle itself, and the apparatus of Japanese Patent Application Laid-Open No. 3-85069 merely displays, in a bottom region of a back area image, the position of a detection sensor closest to an obstacle among three detection sensors, by means of a horizontally extending bar.
However, in actuality, accurately specifying an obstacle closest to a vehicle is often difficult.
Further, for a driver who backs a vehicle while viewing the back area image, roughly displaying on the image an area in which an obstacle is present is sometimes better than accurately specifying an obstacle closest to the vehicle. Specifically, the rough display of an area including an obstacle enables the driver to know an area to which he or she must pay attention and to perform a proper collision avoiding operation before the vehicle collides with an obstacle.
Moreover, a location to which the driver must pay attention can be highlighted, when an area in which an obstacle is present is displayed in such a manner that the brightness, which represents the degree of danger (i.e., the likelihood of collision), decreases gradually from the center or origin of the area toward the periphery thereof, without clearly displaying the boundary of the area. Such display enables the driver to grasp the danger area roughly, thereby facilitating the driver's maneuvering of the vehicle while viewing the image.